(a) Field of the Invention
The present invention relates to an apparatus and a method for calculating a regenerative braking amount of a hybrid electric vehicle, more particularly, to an apparatus and a method that calculate a torque of a wheel axle depending on a motor, and calculate a regenerative braking amount based on the torque of the wheel axle.
(b) Description of the Related Art
Generally, a hybrid electric vehicle is powered by an engine which generates torque from fuel combustion and an electric motor which generates torque from an electric battery.
Hybrid electric vehicles use regenerative braking technology when a braking control according to a brake pedal is performed. In particular, the regenerative braking of the hybrid electric vehicle is a technology which applies a counter torque to the motor by using energy generated during braking to generate electric energy and stores the generated electric energy in a battery.
In the case of regenerative braking, a hybrid controller (HCU) calculates a total braking amount and a regenerative braking amount by considering an operating state of the motor when a driver requests to brake. In addition, an electric brake system (EBS) also calculates the total braking amount and controls hydraulic pressure supplied to a brake cylinder of a wheel in order to satisfy the total braking amount.
In particular, regenerative braking performs braking based on a cooperative control of the EBS which plays a part in hydraulic pressure braking and the HCU.
However, in a transmission mounted electric device (TMED) type of the hybrid electric vehicle which includes a multistage transmission, the hybrid electric vehicle calculates the regenerative braking amount based on a real torque of the motor positioned at a front end of the transmission. If the regenerative braking amount is calculated on the basis of the motor, the regenerative braking amount which is transmitted to the wheel may not be accurately calculated according to a disturbance such as a shift characteristic or a torque characteristic of the motor.
According to the conventional art, regenerative braking amount cannot be calculated because the conventional art does not consider the torque characteristic of the motor and a shift characteristic of multistage transmission that are changed by a charging limit of the motor. Accordingly, the regenerative braking amount is output too much or too little and the total braking amount is changed, so a slip or a shock may be generated during braking.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.